Multi-wavelength Ellipsometer with Fresnel Cone and Diffractive Element
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ellipsometers require rotating optics, which are slow and complex, limiting the speed and accuracy of full Mueller matrix measurements across multiple wavelengths.
Innovation Solution
An ellipsometer using a broadband light source and a Fresnel cone with a diffractive element and meta-grating to spatially separate wavelengths and polarization states, allowing for simultaneous measurement without moving parts and a single beam path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotating optics are used to generate ellipsometric measurements, then the measurement can be completed, but the measurement speed is slow
Solution Approach 1:
The patent replaces the mechanical rotating optics system with a static optical system using a Fresnel cone and diffractive elements. The Fresnel cone generates multiple polarization states simultaneously without mechanical rotation, and the diffractive element spatially separates wavelengths for parallel detection, eliminating the time-consuming sequential measurement process of rotating optics.
Solution Approach 2:
The patent segments the measurement process by spatially separating different wavelengths using a diffractive element and detecting them simultaneously across multiple spectral bands. This parallel segmentation of the spectrum allows all wavelengths to be measured at once rather than sequentially, dramatically increasing measurement speed.
2Adaptability or versatility
If rotating optics are used, then full Mueller matrix measurement is achieved, but the system complexity increases
Solution Approach 1:
The patent eliminates complex mechanical rotating components by using a Fresnel cone to generate multiple polarization states and a diffractive element to separate wavelengths. This static optical system achieves full Mueller matrix measurement capability without the mechanical complexity of rotating polarizers, analyzers, or compensators.
Solution Approach 2:
The Fresnel cone serves multiple functions simultaneously: it generates multiple polarization states, disperses wavelengths through diffraction, and enables parallel detection across the spectrum. This multi-functional element replaces what would traditionally require multiple separate rotating optical components, reducing overall system complexity.
3Productivity
If four separate PSDs with beam splitters are used, then simultaneous polarization state measurement is achieved, but the number of beam paths increases making calibration and alignment difficult
Solution Approach 1:
The patent merges the wavelength separation and polarization state analysis functions into a single integrated detection path using a diffractive element combined with a Fresnel cone. Instead of four separate beam paths requiring independent alignment, all wavelengths and polarization states are processed through one unified optical path, dramatically simplifying calibration and alignment procedures.
Solution Approach 2:
The diffractive element combined with the Fresnel cone performs multiple functions in a single component assembly: wavelength separation, polarization state generation, and spatial encoding. This universal optical element replaces the complex four-beam-path system, making the instrument easier to calibrate and align while maintaining simultaneous measurement capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces measurement time, enhances accuracy, and simplifies calibration, enabling faster and more precise determination of at least a partial Mueller matrix for samples across multiple wavelengths.
Implementation Method 1
The detector includes a diffractive element to spatially separate the wavelengths of the light from the sample
Implementation Method 2
A conventional spectroscopic ellipsometer includes a broad band light source, a polarization state generator
Implementation Method 3
detect changes in the polarization state of light reflected from a surface of a sample
Implementation Method 4
a polarization separator that receives the reflected light and separates the reflected light into a plurality of polarization states
Data Source
AI summary
An ellipsometer uses a broadband light source and a Fresnel cone to produce a simultaneous broadband polarization state generator with no moving parts. The detector of the ellipsometer includes a diffractive element to spatially separate the wavelengths of the light from the sample. The wavelengths may be spatially separated sufficiently that there is no overlap of bands of wavelengths when imaged by a two-dimensional sensor or may be temporally separated. Additionally, the detector separates and simultaneously analyzes the polarizations states of the light from the sample so there is no overlap of polarization states when imaged by a two-dimensional sensor and no moving parts are used. The resulting image with separated wavelengths and polarization states may be used to determine at least a partial Mueller matrix for the sample.